Work done by man pushing a crate up a ramp, includin done on

AI Thread Summary
The discussion focuses on calculating the work done by an 85 kg man pushing a crate 4.00 m up a ramp at a 20-degree angle while exerting a force of 500 N parallel to the ramp. Participants explore the appropriate strategy for determining the force acting on the man and whether to include the crate's force on him. The work-energy theorem is referenced to assess the work required to move the man up the ramp without the crate. Clarification is sought on the angle used in the work formula, with consensus that it should be zero since the force is applied parallel to the ramp's angle. The conversation emphasizes the importance of accurately calculating work done on both the crate and the man.
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Homework Statement


Calculate work done by an 85 kg man who pushes a crate 4.00 m up a ramp at an angle 20 degrees to horizontal.
He exerts a force of 500N on the crate parallel to the ramp, and moves at constant speed.
Include the work that he does on the crate and on his body to get up the ramp.

Homework Equations


I need to find the Force with which he moves himself up the ramp in other to determine the work he does on his body.
I set up x and y components of the forces acting on the man to find the Force, and have come up with a negative magnitude.

--Is setting the x and y components for the forces acting on the man the appropriate strategy?
-- do I include the force of the crate on the man?

The Attempt at a Solution


file attached
 

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Suppose for a moment that it was only the man on the ramp (no crate). What work is required to move him 4 meters up the ramp? What force is he working against? Hint: work-energy theorem.
 
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gneill said:
Suppose for a moment that it was only the man on the ramp (no crate). What work is required to move him 4 meters up the ramp? What force is he working against? Hint: work-energy theorem.

thank you
 
In your attached work you had this portion:
upload_2016-11-25_6-22-46.png


In the indicated equation what does the angle θ represent? Why did you set θ = 20° in the next line?
 
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Should angle θ be "0"
because the force applied is parallel to the angle of the ramp?

W =F d cos(θ) = 500 kg 4 m cos(0) = 2000 J , work done on crate
 
SDTK said:
Should angle θ be "0"
because the force applied is parallel to the angle of the ramp?

W =F d cos(θ) = 500 kg 4 m cos(0) = 2000 J , work done on crate
Yes. The force is applied in the same direction as the motion.
 
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